1. Epidermal vs Ground vs Vascular Tissue Systems
| Tissue system | Components | Location / function |
|---|---|---|
| Epidermal | Epidermal cells, stomata, trichomes and root hairs | Outermost covering; protection, gaseous exchange, transpiration control and absorption |
| Ground / fundamental | Parenchyma, collenchyma and sclerenchyma | All tissue except epidermis and vascular bundles; cortex, pith, pericycle, medullary rays and mesophyll |
| Vascular / conducting | Xylem and phloem | Transport; together form vascular bundles |
Quick distinction Root hairs are unicellular epidermal extensions; shoot trichomes are usually multicellular and reduce water loss.
2. Vascular Bundle Arrangements
| Arrangement | Definition | Occurrence / implication |
|---|---|---|
| Radial | Xylem and phloem occur alternately on different radii | Roots |
| Conjoint | Xylem and phloem lie together on the same radius; phloem usually outside xylem | Stems and leaves |
| Open | Cambium occurs between xylem and phloem | Dicot stems; secondary xylem and phloem can develop |
| Closed | Cambium absent | Monocot stems; secondary tissues not formed |
3. Dicot Root vs Monocot Root
| Feature | Dicot root | Monocot root |
|---|---|---|
| Xylem bundles | Usually 2-4 | Usually more than 6 (polyarch) |
| Pith | Small or inconspicuous | Large and well developed |
| Secondary growth | Occurs; cambium ring develops later | Absent |
| Shared anatomy | Epiblema with root hairs, cortex, endodermis, pericycle, radial vascular bundles and pith | |
| High-yield term | Casparian strips are suberin deposits in radial and tangential walls of endodermal cells. | |
4. Dicot Stem vs Monocot Stem
| Feature | Dicot stem | Monocot stem |
|---|---|---|
| Hypodermis | Collenchymatous | Sclerenchymatous |
| Ground tissue | Differentiated into cortex, endodermis, pericycle, medullary rays and pith | Large, conspicuous, undifferentiated ground tissue |
| Vascular bundles | Arranged in a ring; conjoint, open and endarch | Scattered; conjoint, closed; bundle sheath surrounds each |
| Phloem parenchyma | Present | Absent |
| Water-containing cavities | Absent | Present within bundles |
| Special term | Endodermis is a starch sheath | Peripheral bundles smaller than central bundles |
5. Dorsiventral (Dicot) vs Isobilateral (Monocot) Leaf
| Feature | Dorsiventral dicot leaf | Isobilateral monocot leaf |
|---|---|---|
| Stomata | Generally more numerous on lower (abaxial) epidermis | Present on both epidermal surfaces |
| Mesophyll | Differentiated into upper palisade and lower spongy parenchyma | Not differentiated into palisade and spongy parenchyma |
| Venation | Reticulate; bundles vary in size | Parallel; bundles nearly similar in size |
| Special cells | Palisade cells are compact, vertical and chloroplast-rich | Bulliform cells occur in grasses along veins |
| Response to water stress | Not characterised by bulliform-cell rolling | Flaccid bulliform cells curl leaf inward to reduce water loss |
Exam clue Scattered, closed bundles with sclerenchymatous sheaths and no phloem parenchyma identify a monocot stem.